Chromium-titanium-silicon alloy



Patented Aug. 8, 1939 UNITED STATES PATENT OFFICE 2,189,193 CHROMIUM- TITANIUM- SILICON ALLOY Maine No Drawing. Application January 6, 1938, Serial No. 183,583

4 Claims. (01. 75-134) My invention consists of the formation of a new and improved alloy for adding titanium to cast iron along with the addition of chromium at the same time with the titanium.

The advantages of adding these two elements of titanium and chromium together to cast iron were described in U. S. Patent No. 1,955,791 granted to me April 24, 1934, but heretofore it was necessary as set forth in my patent to make 10 these additions by means of two separate ferroalloys, since no combined alloy of chromium and titanium was known that was practical for use in cast iron at ordinary foundry temperatures.

My new alloy is practical for this purpose, since 15 it also contains silicon in an amount properly related to the chromium and titanium contents therein so as to promote ready solubility in the molten cast iron. The iron content of my new alloy is therefore necessarily low, and the carbon 20 content is also low for the same reason that the silicon content is high, in orderto confer suitable fusibility and solubility in the molten iron.

Obviously it is more convenient and advantageous to add the two alloying elements of chro- 25 mium and titanium to cast iron by a singlelowiron alloy, than by the use of two separate ferroalloys, which latter practice involves the addition of so much more cold material to the molten iron after it has left the furnace. has an advantage over the grade of ferro-chromium now generally used for cast iron in that its carbon content is low, so that the chromium added by my new alloy is not already combined with carbon, but such chromium is more free to 35 distribute itself through the matrix of the iron homogeneously instead of as isolated particles of chromium carbide.

Up to the present time my new combined alloy of titanium and chromium has been made with its approximate composition within the following limits:

, Percent Titanium 10.65 to 29.55 Chromium 14.52 to 41.69 45 Iron 7.42 to 21.73 Silicon and impurities 26.28 to 46.07

My new alloy also C Permissible Average 9 Percent Percent Titanium to 30 20 5 Chromium to 45 30 Iron 0 to 25 12 Sllieon to 45 35 Carbon 0 to 1 (J. 4 Aluminum 0 to 3 1.0 Other impurltie 0 t0 5 1. 6

The preferred analysis of course would be one showing no iron, carbon, aluminum, or other impurities, but this is practically impossible of attainment at a reasonable cost because of the lack of purity of the ores which must be used in com- 15 mercial practice.

My new alloy may be made in the usual type 'of single-phase carbon-lined electric furnace such as is used for making ferro-titanium.

The following example will show one practical 2'0 method of manufacture of this alloy.

An intimate mixture of 150 lbs. of granular rutile, 175 lbs. of chrome ore, 165 lbs. of 90% ferro-silicon, and 30 lbs. of sodium chlorate was first prepared. The rutile contained about 92.5% TlOz, 4% ZrOa, 2.7% S102 and 0.22% F6203, and was crushed so that 98% passed through a 80 mesh screen. The chrome ore was crushed finer than 20 mesh and contained about 54.8% CI203, 14% FeO. 4.5% S102, with the balance alumina, magnesia, etc. The ferro-silicon, containing less than 10% iron, was crushed through a 20 mesh screen.

This mixture was charged gradually for about an hour into a hot electric furnace with a 16 in. square carbon electrode, operating at 50 volts and about 10,000 amperes. About 10 minutes after the charge was completely added, the furnace was tapped into a cast iron mold, and the alloy and slag were allowed to cool. When cold the slag was separated, and 202 lbs. of this new alloy was recovered, containing approximately 20.62% titanium, 26.71% chromium, 12.42% iron, and 40.25% silicon plus impurities.

A higher-grade alloy could readily be made by using a higher-grade chrome ore, containing a lower percentage of FeO. It is also possible to make my new alloy by a slight modification of the method disclosed in my U. S. Letters Patent No. 1,946,670 dated February 13, 1934, the change required being a substitution of highgrade chrome ore for a suitable proportion, of the titanium are in the charge. This method, however, does not involve the use of high-grade ferro-silicon, and hence is more economical of 66 materials, but requires a longer period oi. operation of the furnace to reduce the necessary silicon from its ore.

In the production of my new alloy by the method just described in the example, a uniform stock of the following analysis was accumulated:

This alloy was used -to treat some gray cast iron melted in a foundry cupola, the amount of the addition of my new alloy being 1% of the Weight of the iron.

Comparative results of tests of the original and treated iron are set forth in the following table:

Plain Same iron Same iron Kind of 11011 gray iron plus 1% plus 1% untreated FeTi CrTiSi Carbon content 3. 38 3. 30 3. 30 Silicon content 2. 41 2. 52 2.63 Titanium content 0. 098 0. 128 Chromium content... 0.23 Tranverse strength, 1 or 1.25" dllllTl 3, 980 4, 070 4, 365 Deflection, in. on 12 in. spam 0.12 0.11 0.105 Tensile strength, lbs. per sq.

in 34, 000 35, 700 38, 700 Brinnell hardness N 106 212 235 The usefulness and value of this new alloy in regular foundry practice are demonstrated by the results given in this table. Its use is not necessarily confined to cast iron, but obviously can be extended to include any metal or alloy in which additions of chromium, titanium, and silicon may be desired, such as steel, nickel, aluminum, or alloys of nickel, copper, etc.

I claim as my invention:

1. An alloy of chromium and titanium for metallurgical use having the approximate composition range: to 30% titanium, to 45% chromium, to 45% silicon, 0.1 to iron, 0.]. to 3% aluminum, 0.01 to 1% carbon, and not over 5% of other impurities.

2. A chromium-titaniuln-silicon alloy consisting of about chromium, 20% titanium, silicon, 12% iron, 0.1 to 3% aluminum and 0.01 to 1% carbon.

3. A chromium-titanium-si1icon alloy consist ing of about 30% chromium, 20% titanium, 35% silicon, 12% iron, 0.4% carbon, 1% aluminum, and 1.6% other impurities.

4. A chromium-titaniumsilicon alloy consisting of about 27% chromium, 23% titanium, 34% silicon, 14% iron, 1% aluminum, 0.40% carbon and 0.60% other impurities.

GEORGE F. COMSTOCK. 

